Said to be the most performed among today’s living composers, a composer whose music is touched with sonic purity and infused with beguiling spirituality, Arvo Pärt is revered as an agent of escape.

When it comes to the favorite composer of all time, Mozart ever tops lists among performers and audiences alike. (He was even John Cage’s favorite composer.)

Pärt reveres Mozart, referring to him as the greatest of them all, especially when it comes to expressing the wonder of the divine spirit. The Mozart & Pärt festival, which the Los Angeles Philharmonic began Thursday night with Gustavo Dudamel, is, therefore, seemingly a natural, even though no one else seems to have thought of it before. The orchestra is promoting the two-week festival with a video on its website as a way to get away from it all, leave behind the hurly-burly of L.A. life in the sanctuary of Walt Disney Concert Hall. Even Mayor Eric Garcetti extols L.A. escapism on the video.

I’m sorry to disappoint. Yes, you have to turn your distracting cellphone off in the concert hall. Yes, Dudamel himself may seem like someone in search of immediate spiritual solace. He is just off a rocky ride in Austria, booed at the Vienna State Opera where he conducted “Turandot” and praised for what was reported as a darkly contentious “West Side Story” with Cecilia Bartoli in Salzburg. Much must furthermore weigh on Dudamel as his native Venezuela descends into economic and political chaos, leaving the fate of hundreds of thousands of El Sistema students uncertain.

And, yes, this is an important festival full of content and meaning that may be lacking in our daily activities. But Thursday’s important concert full of content and meaning, pitting Pärt's merciless “Miserere” with Mozart’s troubling and dispiriting Requiem, left no place for escape. This is music of intense, relentless authority that confronts mortality and of the overwhelming physicality of the world, and Dudamel’s performance had the character of inescapable prophesy. You want peace? A traffic jam later that evening turned the 10, by comparison, into a serene freeway.

“Miserere” is both important and disturbing. Written in 1989, it became a key work in the development of Pärt’s personal style, which the 80-year-old Estonian composer calls "tintinnabuli." At its simplest, this technique mimics the resonance of bells. A melodic line is sheltered by another line that outlines the harmonic spectrum, causing the melody to grow into something more oracular than auricular.

However miraculous, the effect is also natural. This is why an early and simple tintinnabuli piano piece such as “Fur Alina” effectively accompanies weddings, funerals and cat videos on YouTube.

In “Miserere,” a stern music for chorus, five vocal soloists and a small ensemble (of winds, brass, electric guitar, electric bass, organ and percussion) proceeds through Psalm 51 a word at a time and note a time. Melodies build very slowly. Accompaniment is gradually added and regularly disappears, leaving us to ponder each note and each word in Latin.

There are chaste consonances that have all the qualities of warmth and comfort, yet so unpolluted are these harmonies that they convey great fragility and unease. (There was much nervous coughing in the hall.) There are also penetrating dissonances, one note pushing against another, that make the whole room vibrate and a listener feel alive and alert. (These produced no nervous coughing.)

And there is shocking anger. Twice Pärt interrupts “Miserere” with the Dies Irae, the Day of Wrath hymn found in requiem masses and meant to warn the living of the horrors facing sinners. Listen to this on recording (there is an excellent one with the Hilliard Ensemble) and it sounds like distortion. It’s not the recording. The performance in excellent Disney acoustic sung by a rapt Estonian Philharmonic Chamber Choir and Latvian Radio Choir were just as distorted. Pärt writes the distortion into the music as if to prove nothing remains pure.

Mozart’s Requiem goes down easier but shouldn’t. Its fragility is merely of a different sort. The composer’s last testament, it was left unfinished and no completion — whether the standard one by Mozart’s pupil, Franz Xaver Sussmayr, or the more recent scholarly ones — is adequate. The result is also the same. Inspired music loses its inspiration as if death were but a trickling toward banality.

Dudamel led “Miserere” pitilessly. He took nothing for granted, refused to soften what is hard and required each sound to undergo the test of time. He gave Mozart’s Requiem operatic expression but again little comfort. Mozart’s Dies Irae needed a rage to match Pärt, and that meant that everything else had to be raised to that kind of emotional level as well. With Pärt setting the stage, Dudamel’s grim yet profound acceptance of the implications the Requiem ultimately proved vivid illustration of what made Mozart Mozart, and hence what makes each thing itself.

He had help from the singers. The choruses from Pärt’s Estonia and from Latvia added a demonstrative emotive aspect to the evening. The commanding, sterling soprano Lucy Crowe dominated the soloist, but not so much as to diminish the excellence of mezzo-soprano Roxana Constantinescu, tenors Paul Appleby and Frederick Ballentine and bass-baritone Luca Pisaroni.